Attorney General Thomas F. Reilly knew from the start how
difficult it would be to bring a criminal indictment against
Cardinal Bernard F. Law and his top deputies for failing to
put a stop to sexual abuse of children by priests.

Not because Reilly, a Catholic, didn't want to. A fellow
prosecutor says Reilly was ''passionate'' about the case and
fully prepared to prosecute the leaders of the Boston archdiocese
for what he considered outrageous misconduct.

But Reilly couldn't proceed because he lacked the legal tools.
Laws that would have eased prosecution didn't exist in Massachusetts
at the time of the offenses. What laws there were required
something he didn't think he could prove: criminal intent.

''The intent by all church leaders was to protect the reputation
of the church,'' Reilly said yesterday. ''The intent was to
maintain secrecy. [But] there was no intent that we have found
to assist in any way in criminal acts.''

In his 76-page report, which directed harsh criticism at
Law and his top bishops in the archdiocese, Reilly said his
staff looked at several criminal statutes to determine if
the evidence would support an indictment. They considered
prosecuting Law and the bishops as accessories before or after
the fact of a felony, for conspiracy, or for obstruction of
justice. They weighed indicting the archdiocese itself for
its failure to intercede to stop the abuses of its agents,
the priests. Even the testimony of the bishops before a grand
jury was scoured to determine if any misstatements might be
sufficient to bring a perjury indictment.

In each case, Reilly and another prosecutor in his office
said yesterday, either insufficient evidence was uncovered
to justify an indictment or there was not a specific statute
on the books that prohibited the conduct.

''Certainly no one is more disappointed than I and my staff
that we cannot prosecute these cases criminally,'' Reilly
told reporters. But to have sought an indictment against any
of the bishops or the archdiocese when the statutes did not
clearly support a charge would have been a violation of his
constitutional responsibilities, he said.

For example, Reilly found that:

Bishop Robert Banks failed in 1989 to tell the Suffolk district
attorney's office, which was investigating a complaint against
the Rev. John Geoghan, that the archdiocese knew of prior
allegations of abuse against Geoghan.

In some states, such a failure to make a full disclosure
to investigators can justify a charge of obstruction of justice.
Similarly, Bishop Alfred Hughes failed to inform prosecutors
in Plymouth County after they had indicted the Rev. John Hanlon
on sexual abuse charges that he had learned of a second Hanlon
victim.

But according to one of Reilly's deputies, the requirements
are stricter in Massachusetts to justify an obstruction of
justice charge. Prosecutors would have had to show that Banks
and Hughes held back the information to interfere knowingly
with the investigations.

Both Cardinal Law and Cardinal Humberto Medeiros, his predecessor,
allowed priests against whom they had received specific allegations
of abuse to be transferred to other parishes inside the archdiocese
or to dioceses in other areas of the country, where they were
accused of further abuse. In some states, Law and Medeiros,
if he were alive, might have been vulnerable to being prosecuted
for such acts as an accessory before or after the commission
of a felony.

In Massachusetts, however, the accessory after the fact statute
requires proof that the aid rendered by Law or Medeiros was
provided with the specific intent of helping an offender escape
prosecution or avoid detection. To prosecute an accessory
before the fact of a felony charge, the prosecutors needed
to show that Medeiros and Law acted with knowledge that doing
so would result in further abuse.

Reilly's office also considered the possibility of bringing
a felony charge against the archdiocese, as a corporation,
for the abuse committed by their priests. Such a prosecution
would rely on a legal theory, set down in decisions of the
Massachusetts Supreme Judicial Court, that holds corporations
responsible for the misdeeds of their agents.

Wendy Murphy, a former prosecutor who focused on child abuse,
urged Reilly's prosecutors to bring the case on such grounds.
But she said they declined on the grounds that the court's
decision requires a showing that the archdiocese benefited
from the abuse by their priests. That was a test Reilly didn't
think prosecutors could meet.

''I was disappointed, but I believe they had an arguable
position,'' Murphy said yesterday.

That Reilly was prepared to seek indictments was clear to
Philip T. McLaughlin, the attorney general of New Hampshire,
whose office gained a settlement in a criminal case against
the diocese of Manchester, N.H., for conduct similar to that
found in Boston. The two men met in Reilly's office before
the Massachusetts investigation was announced.

''From what I observed, he had a passionate commitment to
go forward, a passionate commitment to bring a criminal case,''
McLaughlin recalled yesterday.

What Reilly was lacking, he said, were two statutes McLaughlin
used in New Hampshire to construct his case: one requiring
that clergy report to civil authorities their suspicions of
child abuse, and another permitting the prosecution of any
person or institution that fails to protect children and thus
endangers them.

The Massachusetts Legislature only last year passed a law
requiring clergy to report suspected cases of child abuse
as well as a child endangerment law.

Gerald D'Avolio, executive director and principal lobbyist
for the Massachusetts Catholic Conference, said that conference
members -- Law and the other three bishops who head dioceses
in Massachusetts -- had not lobbied against earlier proposals
during the 1990s, even though they were concerned that, under
a reporting law, priests might be forced to divulge information
learned during confessions.

The proposals ''just never got enough steam during those
years for us to have to take a position,'' D'Avolio said yesterday.
The conference backed the proposal in 2001 once legislators,
spurred by publicity over the Geoghan case, began talking
seriously about the proposal.

Senator Mark C. Montigny, a New Bedford Democrat who had
sponsored clergy reporting bills since the mid-1990s, said
that Law and the three other bishops had a ''moral obligation''
to support the proposal long before 2001.

''The bishops were the only ones who knew how serious the
problem was, how many priests deserved to be reported to authorities,''
Montigny said yesterday.